In recent years, wireless communications requiring no communication cables are widely used. In these days, ultra-wideband (UWB) communication which can be performed using a bandwidth of several GHz at such a high rate of several hundred Mbps has been collecting attention. The ECMA-368 (European Computer Manufacturer Association-368) is a standard for UWB communication. In the ECMA-368 standard, only two layers are defined, physical layer and media access control (MAC) layer. It is therefore possible, when necessary to realize an application requiring high-speed wireless communication, to define a protocol for a higher layer than the MAC layer.
In the ECMA-368 standard, bandwidth management for devices present in a same network is not defined. For each application, therefore, it is necessary to define a bandwidth management arrangement as a higher-layer protocol than the MAC layer.
In Wireless USE (registered trademark, hereinafter omitted), which is an ECMA-368 based application, for example, a device called a host controller (hereinafter referred to as a “host device”) provided with a module performs bandwidth management. To be concrete, the host device secures a bandwidth for the whole network in advance and, every time an additional device joins the network, the host device allocates a bandwidth to the additional device.
There are also bandwidth management methods applied when using a wireless interface (IF) which is not an UWB interface. In one of such methods, communication line utilization efficiency is improved by calculating an optimum bandwidth for use in stream data exchanges based on information about the condition of communication, for example, packet intervals (see Patent Document 1). In another of such methods, the condition of utilization of each service executed on a network is observed, a bandwidth to be made available for each service is calculated based on the condition of utilization and service priority, and picture quality is converted based on the calculated bandwidth value (see Patent Document 2).    Patent Document 1    Japanese Unexamined Patent Publication No. 2009-49514    Patent Document 2    Japanese Unexamined Patent Publication No. 2008-311902